Blast cleaning system

ABSTRACT

A scouring or blast cleaning system wherein a supply of flowable abrasive material is introduced into suspension in a flowing stream of fluid within an injector device and the resulting stream then flows out of the injector device and is impinged upon the object to be scoured.

United States Patent Goss et al. 1 Sept. 12, 1972 [54] BLAST CLEANING SYSTEM 2,040,715 5/ 1936 Smith ..51/11 X 2] Inventors: John B. Goss; John E- stachowiak, 2,107,084 Pletcher ..51/11 both of Houston 2,114,573 4/1938 Rhodes ..5l/321 2,369,576 2/1945 Keefer ..51/11 [7 Asslgneer Amerlcan Aero Engmeenng 2,489,097 11/1949 Luce ..51 11 x P 3,069,812 12/1963 Shelton ..51/11 22 Filed; Jan. 25 1971 3,212,217 10/1965 Furgason ..51/8

[21] Appl' 109,123 Primary Examiner-Donald G. Kelly Att0meyPravel, Wilson & Matthews [52] US. Cl. ..51/11 51 Int. Cl. ..B24c 5/04 7] ABSTRACT [58] Field of Search ..51/8, 11, 319, 321 A scouring or blast cleaning System wherin a Supply [56] R f Cted of flowable abrasive material is introduced into e erences I suspension in a flowing stream of fluid within an injec- UNITED STATES PATENTS tor device and the resulting stream then flows out of the injector device and is impinged upon the object to 108,408 I 10/1870 Tllghman ..51/11 X vbe scourmi 992,144 5/1911 Babcock ..51/11 X 1,026,688 5/1912 Macleod et al. ..51/11 X 4 Claims, 3 Drawing Figures /0 /Za za m A? /?b ?b I, 022 A? 290 3 d I 4 l //X q f Z4 0 //1 3 /Je /r //d I -1- f 2/ U77 g 30 7 6 l n14 /3c /0 l e /de BLAST CLEANING SYSTEM BACKGROUND OF THE INVENTION The field of this invention is a system for scouring an object with flowable abrasive material suspended in a flowing stream of fluid.

For many years various objects have been cleaned by scouring with sand and other flowable abrasive materials. Sand blasting usinga flow of air as a fluid carrier has been the most common method of scouring, but because of the resulting air pollution, its use has recently been restricted. Wet abrasive cleaning equipment using a liquid carrier has also been used wherein the abrasive and fluid were combined in an injector device such as that in US. Pat. No. 2,489,097. In such devices, the cleaning discharge pattern was neither uniform nor symmetrical. The uneven distribution of abrasive also caused rapid localized uneven errosion of portions of the discharge nozzle throat further downgrading effectiveness of the cleaning discharge pattern and requiring frequent nozzle replacement.

SUMMARY OF THE INVENTION Briefly, this invention relates to a blast cleaning or scouring system, including an injector device for uniformly introducing flowable abrasive material for straight-through flow into suspension in a liquid which is also introduced into the injector device and then discharging the resulting stream from the injector device in a symmetrical pattern upon the object to be scoured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is partly schematic view of the overall system of the present invention; and

FIG. 2 is a vertical sectional view of the injector device forming part of the system illustrated in FIG. 1;

FIG. 3 is a vertical sectional view of the injector device taken along line 3-3 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, the letter S generally designates the scouring system of the present invention including a supply of abrasive A, a supply of water or other fluid F, an injector device D, shown in greater detail in FIG. 2, and control means B and pump 3 for controlling the supply of sand or other abrasive and the flow of liquid, respectively, to the injector device D.

Considering the invention in greater detail, the fluid supply F illustrated in FIG. 1 as the preferred embodiment includes a tank 1, filled with liquid, communicating through conduit 2 with the high pressure pump 3, which is preferably a positive displacement pump, for supplying a liquid, usually water, to the pump 3 which may be of any suitable type. The pump 3 discharge communicates with the injector device through a conduit 4, preferably a flexible hose for supplying a flow of fluid under pressure to the injector device D. Means for controlling the flow of liquid through conduit 4 to the injector device D is preferably provided by regulating the speed of the positive displacement pump 3. Other liquid control means, such as a valve, may be employed with other types of pumps. The present invention is not to be limited to the preferred fluid supply system illustrated and described herein. Other liquid supply systems may be employed as well as pneumatic or other fluid systems.

The preferred embodiment means for supplying or feeding flowable abrasive material A to the injector device D includes a reservoir or tank 5 filled with flowable abrasive material, normally sand, communicating with the injector device D through a conduit 6. The conduit 6, like the conduit 4, is preferably a flexible hose. The abrasive supply control means B is mounted with the conduit 6 for controlling the entry of the abrasive material to injector device D. As illustrated in FIG. 1, the preferred embodiment of the abrasive control means B uses a fast acting valve, such as a ball valve, but other suitable types of valves may be employed. Other equivalent systems of supplying the abrasive material to the injector device will be apparent to those skilled in the art.

FIG. 2 illustrates the relationship of the abrasive supply conduit 6 and the fluid supply conduit 4 to the injector device D. The injector device D comprises a body 10, a nozzle 11, an inlet means or member 12 and an effluent means or member 13. The body 10 is a cylindrical sleeve, having a cylindrical chamber therein extending from one end of the sleeve 10 to the other. The body 10 is threaded on the inner surface at both ends 10a and 10b. The inlet member 12 communicates the flow of flowable abrasive material from the abrasive supply means conduit 6 to the chamber 10c of the body member 10. The inlet member 12 is a special pipe bushing extending within the chamber 100 and having outer threads 12a engaging the threads 10a of the body 10 for securing and sealing the inlet member 12 to the body member 10. The distance which the inlet member 12 extends into the chamber we is fixed by shoulder 12b contacting the body 10. The abrasive supply conduit 6 is secured and sealed at one end to the inlet member 12 by threaded engagement of threads 6a with inner threads on the inlet member 12. A pair of stepped shoulders 12d and 12e at the inner end of the member 12 bear against the nozzle 11 so that in conjunction with the shoulder 12b which engages the body 10,-position and secure the nozzle 11 within the body 10 in a manner to be more fully described hereinbelow. 7

The fluid supply conduit 4 is secured to the body 10 .and is sealed thereto by a threaded portion 4a of conduit 4 engaging threads 10e of an opening 10d in the body 10.

The effluent member 13 for flowing the resulting stream of fluid with suspended flowable abrasive material therein out of the chamber 100 is illustrated in FIG. 2 as a cylinder extending within the chamber 10c and having a tapered opening 13a extending therethrough. Threads 13b on the outer cylindrical surface engage threads 10b on the inner surface of body 10 for securing and sealing the eflluent member 13 to the support body 10. A shoulder at one end of the efiluent member 13 bears against the end of the nozzle 11 opposite the inlet member 12 and thus acts with the shoulders 12d and He of the member 12 to secure the nozzle 11 in a predetermined position within the chamber 100 of the body 10.

In the preferred embodiment illustrated in FIG. 2, the effluent member 13 has a second nozzle 13d formed therewith which has a tapered restricted opening 13e therethrough for directing and increasing the velocity of the resulting stream flowing out of the chamber 100 through the opening 13a in the effluent member 13. The discharge from the nozzle 13d is directed to impinge upon the object to be scoured. The preferred embodiment includes the second nozzle 13d in the injector device D in order to minimize plugging of the effluent means 13 by abrasive material settling out of suspension, but the second nozzle can be remote from the injector device D.

The nozzle 11 is cylindrical and is a sleeve positioned within the chamber c in a concentric manner for introducing the flowing stream of fluid into the chamber 10c. As previously noted, the nozzle 11 bears against the stepped shoulders 12d and 12e of the inlet bushing 12 which in conjunction with the shoulder 130 of the effluent member 13 secures the nozzle 11 in the chamber 10c of the body 10. The nozzle 11 has a bore 11a and a restricted smaller diameter bore 11b therethrough, leaving the chamber 10c unfilled by such bore portions of the nozzle 11, allowing the abrasive inlet member 12 to communicate with the effluent member 13. The openings 11a and 11b serve as a nozzle for the flowable abrasives, both of which are preferably concentric to the axis of the nozzle 11, to give a uniform symmetrical axial or straight through flow of abrasive through the injector device chamber 10c, and because of the concentric relationship of the nozzle 11 and body 10, also concentric to the axis of the chamber 101:. Tapered surfaces 110 and 11d are provided to enhance the flow of abrasive from the inlet member 12 through the openings 11a and 11b in a manner to be more fully described hereinafter.

An indented or inclined annular opening 11f extending around the outer surface of the nozzle 11 communicates with the opening 10d in the body 10 to serve as a manifold for the fluid introduced into the chamber 100. A pair of O-rings 20 and 21, formed of rubber or similar material, fit within a pair of grooves 11m and lln, respectively, on the nozzle 11 and complete the manifold'by sealing the nozzle 11 to the body 10 on both sides of the opening 11f. The illustrated indented opening of FIG. 2 is shown with an inwardly and forwardly tapered surface 11g and a forward surface 11h substantially perpendicular thereto, but such opening 11f may have other shapes so long as the liquid is properly directed as will be more evident hereinafter.

A plurality of nozzle openings lle, two of which are illustrated in FIG. 2, extend through the nozzle 11 from the annular opening 11f for flowing the fluid from the manifold 11f into the chamber 10c. The illustrated nozzle openings lie are also preferably restricted at nozzle passages lli. An annular portion 11k of the nozzle 11 adjacent the discharge outlets of the plurality of nozzles He, is preferably beveled perpendicularly to the axis of the smaller nozzle passages lli. Each of the other of the plurality of nozzle openings includes the identical structure.

The plurality of nozzle openings lle are preferably located equidistant from the axis of the chamber 100 and are preferably uniformly distributed around the circumference of the chamber 100. As illustrated in FIG. 3, each of the nozzle passages lli is located adjacent the chamber We in a circular vee notch or groove llz recessed into the annular portion 11k of the nozzle 11. The groove llz tends to radially confine the discharged flow of fluid from nozzle passages lli while distributing such fluid along an arc formed by a portion of the circumference of groove llz. The groove llz thereby serves as the means for forming the fluid flowing from each of the plurality of nozzles 1 1e into a fanshaped fluid discharge pattern. With this arrangement the exit opening of each of the nozzles lli is also directed obliquely to the chamber axis to provide a flow of fluid to intersect at a common point 30 forwardly of the nozzle 11, whereby the flow of fluid into the chamber is in the form of a surface of a cone having a vertex at the point 30 where the flow from the nozzle openings lle intersects. The point of intersection may be within or outside of the chamber 100, but

preferably it is located on the central longitudinal axis of the chamber 100 or on the central longitudinal axis of the chamber effluent opening 13a. To enhance the effect of the fluid introduced into the chamber 10c, the

- chamber effluent opening 13a should be frusto-conical or tapered to parallel the surface of the cone generated by the fluid introduced from the nozzle openings lle into the chamber 10c. Such an arrangement also prevents build-up of abrasive material in the effluent member 13.

As illustrated in FIG. 2, the vertex of the cone formed by the flow of fluid into the chamber 10c may be located within the second nozzle 13d and on its axis. Such an arrangement minimizes the fluid pressure drop through the injector device D.

In the use and operation of the present invention, the injector device D is assemblied by screwing the inlet member 12 into the body 10 until shoulder 12b contacts the body 10. The O-rings 20 and 21 are placed within their respective grooves 1 1m and 1 In in the nozzle 11, and the nozzle 11 is thereafter inserted into the chamber 10c of the body 10. The eflluent member 13 is then screwed into the body 10 to secure the nozzle 11 in position. The abrasive supply conduit 6 and the conduit supply 4 are then connected to the injector device.

Fluid flow is then established through the injector device D by the operator starting the positive displacement pump 3. This admits fluid to the manifold 11f for fan-shaped flow into the chamber 100 through the plurality of nozzle openings lle in the nozzle member 11. The flow of fluid exits the chamber 10c at high pressure through effluent opening 13a and the second nozzle opening 13e.

The high speed exit of the fluid from the nozzle 11 generates an area of reduced pressure within the chamber 100 and causes a flow of any abrasive material in the nozzle 11 or in communication therewith, as will be more evident hereinafter. With the preferred embodiment the area of reduced pressure within the chamber 100 formed by the intersecting arrangement of the flow from the plurality of nozzle openings lle, is located adjacent the effluent opening 13a.

The operator normally adjusts the flow through the injector device D by speeding up or slowing down pump 3 while observing the fluid flow discharge pattern from the second nozzle opening 13e. After obtaining the desired discharge flow pattern from second nozzle opening 13c, the operator opens the abrasive control valve B. The abrasive material will then flow through the conduit 6 and the inlet means 12 into the chamber 100 because of the reduced pressure portion of the chamber 10c generated by the high speed flow of fluid from the plurality of nozzle openings 11e. Because of the restricted passage or bore 11b in the nozzle 11, a venturi effect is created through the nozzle to facilitate high speed axial or straight through flowing of the abrasive material through the nozzle 11 from the supply 5. As the increased velocity abrasive flows into the reduced pressure area, it comes into contact with the high velocity water or liquid to mix therewith and to form a resulting stream of uniformly and symmetrically suspended fluidized abrasive 'material for discharge from the effluent means 13.

The abrasive carried away in the resulting stream is continuously fed into and axially or straight through the chamber 10c, so long as the valve B is open, by additional abrasive flowing into the chamber 10c from the tank 5. In this manner the injector device D continuously introduces the flowing abrasive material into suspension in a flowing stream of fluid. In the illustrated embodiment, the axis of the axially or straight abrasive injection nozzle 11 coincides with the axis of the surface of the fluid cone formed by the fluid flowing from the plurality of nozzle openings lle. As the abrasive flows toward the vertex of the cone, the nozzle-like opening 11b forms the abrasive into a circular crosssectional shape, as well as increasing its flow velocity. The outer edge or circumference of the abrasive flow cross-section uniformly and symmetrically contacts the conical fluid pattern which constantly removes or shaves the outer edge of the flow of abrasive, reducing the size of the circular cross-section until the abrasive stream cross-section is reduced down and coincides approximately with the liquid stream at the vertex 30 of the fluid flow. Since the abrasive is continuously axially flowing into the chamber so long as the supply lasts and the valve B is open, the abrasive stream is shaped as a cone in the contact area with a taper corresponding to the flow of fluid from the plurality of nozzle openings 1le. With this preferred arrangement, the contact, entrainment, interface, or exposure area of the abrasive to the fluid is also shaped like the surface of a cone, is relatively large and the abrasive is continuously, uniformly and symmetrically fed to the fluid through this area. All of this is accomplished with a minimum pressure loss by the fluid flowing through the injector device.

The operator having set the fluid flow pattern from the second nozzle opening 13e before opening abrasive valve B need only direct the resulting stream of abrasive material uniformly suspended in the fluid where it will impinge or contact the object to be blasted, cleaned or scoured. When the desired degree of blast cleaning is achieved, the operator closes the abrasive valve B, cutting off the supply of abrasive material to the chamber 100. After a suitable period of time, to allow the abrasive in the chamber 100 and inlet member 12 to be introduced into suspension in the flowing stream of fluid and not to remain in the injector device D where it may plug the passages or nozzles, the pump 3 is stopped.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials as well as in the details of the illustrated construction may be made within the scope of the appended claims without departing from the spirit of the invention.

We claim:

1. An injector device for continuously introducing a flowing abrasive material into suspension in a flowing stream of liquid, comprising:

a. a body having a chamber therein;

b. inlet nozzle means mounted with said body upstream from and having an axial bore communicating with said chamber for flowing abrasive material axially through said chamber;

. effluent nozzle means connected with said body and disposed downstream from said chamber for flowing out of the chamber the abrasive material suspended in a flowing stream of liquid;

. a plurality of nozzle openings disposed in said inlet nozzle means around said axial bore thereof for introducing liquid into said chamber from externally thereof for creating a liquid flow in said chamber to feed said abrasive material in suspension with said liquid for flow therewith in a stream at high pressure through said effluent nozzle means;

. a liquid inlet tube for connection with a source of liquid under pressure and extending into said body from externally thereof for supplying liquid for flow through said nozzle openings;

. said plurality of nozzle openings for introducing fluid into said chamber being positioned obliquely at an angle to the axis of said chamber for directing the flowing stream of liquid from each of said nozzle openings in a direction to intersect the flowing stream of liquid from each of the remainder of said plurality of nozzle openings at a common point located substantially on the axis of said chamber wherein the surface of flowing liquid generated by said plurality of nozzle openings is that of a cone having a vertex located substantially on the axis of said chamber;

g. the wall of said chamber being conically shaped to substantially the same shape as that of said cone formed by the flowing liquid discharged from said nozzle openings and terminating at substantially the vertex of said cone and merging at that point with the wall of the effluent nozzle means; and

b. said efiluent nozzle means having a bore disposed downstream from said chamber for conducting the abrasive material and liquid axially beyond said vertex before discharging same.

2. The injector device as set forth in claim 1,

wherein:

each of said nozzle openings has an enlarged discharge opening for forming the flowing stream of liquid introduced within said chamber from each of said plurality of nozzles in a fan-shaped pattern.

3. The injector device as set forth in claim 2,

wherein:

said inlet nozzle means includes a circular vee groove recessed into said inlet nozzle means adjacent said chamber; and

said enlarged discharge openings in said nozzle openings for introducing liquid into said chamber are located within said groove.

4. The injector device set forth in claim 1, wherein:

said bore of said effluent nozzlemeans is tapered and reduced in diameter from said chamber to its discharge opening to increase the velocity of the stream of abrasive and fluid discharged therefrom. 

1. An injector device for continuously introducing a flowing abrasive material into suspension in a flowing stream of liquid, comprising: a. a body having a chamber therein; b. inlet nozzle means mounted with said body upstream from and having an axial bore communicating with said chamber for flowing abrasive material axially through said chamber; c. effluent nozzle means connected with said body and disposed downstream from said chamber for flowing out of the chamber the abrasive material suspended in a flowing stream of liquid; d. a plurality of nozzle openings disposed in said inlet nozzle means around said axial bore thereof for introducing liquid into said chamber from externally thereof for creating a liquid flow in said chamber to feed said abrasive material in suspension with said liquid for flow therewith in a stream at high pressure through said effluent nozzle means; e. a liquid inlet tube for connection with a source of liquid under pressure and extending into said body from externally thereof for supplying liquid for flow through said nozzle openings; f. said plurality of nozzle openings for introducing fluid into said chamber being positioned obliquely at an angle to the axis of said chamber for directing the flowing stream of liquid from each of said nozzle openings in a direction to intersect the flowing stream of liquid from each of the remainder of said plurality of nozzle openings at a common point located substantially on the axis of said chamber wherein the surfacE of flowing liquid generated by said plurality of nozzle openings is that of a cone having a vertex located substantially on the axis of said chamber; g. the wall of said chamber being conically shaped to substantially the same shape as that of said cone formed by the flowing liquid discharged from said nozzle openings and terminating at substantially the vertex of said cone and merging at that point with the wall of the effluent nozzle means; and h. said effluent nozzle means having a bore disposed downstream from said chamber for conducting the abrasive material and liquid axially beyond said vertex before discharging same.
 2. The injector device as set forth in claim 1, wherein: each of said nozzle openings has an enlarged discharge opening for forming the flowing stream of liquid introduced within said chamber from each of said plurality of nozzles in a fan-shaped pattern.
 3. The injector device as set forth in claim 2, wherein: said inlet nozzle means includes a circular vee groove recessed into said inlet nozzle means adjacent said chamber; and said enlarged discharge openings in said nozzle openings for introducing liquid into said chamber are located within said groove.
 4. The injector device set forth in claim 1, wherein: said bore of said effluent nozzle means is tapered and reduced in diameter from said chamber to its discharge opening to increase the velocity of the stream of abrasive and fluid discharged therefrom. 